Fluid meter



FLUID METER Filed June 29, 1945 2 Sheets-Sheet l INVENTOR. EMORY FRANK STOVER E. F. STOVER FLUID METER May 23, 1950 Filed June 29, 1945 2 Sheets-Sheet 2 INVENTOR. EMORY FRANK STOVER Patented May 23, 1950 UNITED S TATES PATENT OFF I CE.

FLUID METER Emory Frank Stovcr, Wynnewood, Pa.

Application June 29, 1945', Serial Nb. 602,183

16 Claims; 1' M This invention relates to fluid meters and more particularly to fluid meters for use in connection wan primary'metering elements such as Venturi tubes, orifices, nozzles and Pitot tubes.

The invention further relates to apparatus for measuring and indicating variations in conditions and forces where it is desired to obtain'a square root relation of the condition or force to be measured.

It is the principal object of'the present invention to provide a fluid meter fordirectly obtaining a square root relation of a differential pressure'or force.

It is a-further object of the present invention to provide a fluid meter for directly obtaining a relation which is a slight departure from the square root relation of a differential pressure or force.

It is a further object of the present invention to provide apparatus employing laminar flow of a pilot fluid in a tube with provisions for vary- 1 ing the eilective length of the tube.

It is a further object of the present invention taprovide apparatus employing laminar flow of a. pilot fluid through a tube which is readily adaptable for diiierent maximum rates of flow in primary elements of different ratios.

It'is a further-object of the present invention to provide improved apparatus for applying an initiai force to a responsive element in opposition to astatic pressure produced by laminar flow for obtaining an indication directly proportional to the-'ini'tial force;

It is a further object of the present invention to provide a fluidj meter capable of operating at the optimum conditions of fl'uid viscosity of a Other objects of the invention willbe apparent from the specification and claims.

' The nature and characteristic features of the invention will be more readily understood from the following description, taken in connection 'with 'the' accompanying drawings forming part showing certain details of'the meter, and- Fig. 3 is a fragmentary vertical sectional" view, further enlarged, through a rod or tube forming part of the meter in accordance with the present invention.

It should, of' course, be understoodthatthedescription and drawings herein are illustrative merely; and that various modifications and changes maybemade in the structure disclosed without departing from the spirit of the inven tion.

Referring more particularly to the drawings in which a preferred embodiment of the invention is illustrated, a primary metering device is shown which is adapted for obtaining a differential pressure or force derived'from fluid flow through conduits in which Venturi tubes, orifices, nozzles, or Pitottubes are connected, or from Pitot tubes employed for obtaining the speed of ships; airplanes, or the like. For purposes of explanation the primary metering device is shown in: the form of a Venturi tube'l'dconnected in a conduit for measuring the rate of flow'of fluid through the conduit H.

The upstream or high pressure side of the p mary metering device Hihas a pipe l2 connected thereto and the downstream or lower pressure portion of the primarynretering device l-U has a pipe l 3' connected thereto.

A sectional casing Ht is provided having a lower end wall [5, an upper end wall I6; and a transverse intermediate wallv H. In the space-between the wall l5" and the wall I! a flexible diaphragm i8 is provided supported by a plate 9 and clamped'by a; plate 20: The diaphragm l8 sep arates a chamber 2| from a chamber 22, in the casing M. The'chamber'zl has thepipe l-2 connected thereto and the chamber 22' has the pipe i3 connected thereto so that the highand lower pressures respectively from the-primary metering device are effective therein. On each side of the diaphragm f8 flexible metallic: bellows 23" and 24, of equal effectiveareaare'provided. Thebehows 2'4 is secured to the wall l5 at. one end and secured tothediaphragm It at the otherend, in fluid tight relationship; The bellows 23'i's secured at one-end to the diaphragm [8 and at the other end tothe wall H, in fluid tight relationship.

Inthe casing 1'4 and above the wall H adiaphragm 25 is provided, supported by a plate and clamped byaplate' 21 The space between the diaphragm 25 and the wall l1, within the casing 14, provides a pressure chamber 28 for purposes to be explained. The interior of the bellows 23 is preferably in communication with the interior of the bellows 24 by means of a port 29 extending through the diaphragm l8 and the interior of the bellows 23 is in communication with the chamber 28 through a passageway 30 through which a valve rod 3| extends. The valve rod 3! is secured to the diaphragm 18 for movement therewith and is secured to the diaphragm 25 for movement therewith.

Within the bellows 24 an adjusting spring 32 is provided, bearing against the lower end of the diaphragm l8 and against a spring plate 33, an adjusting screw 34 being in engagement with the lower end of the spring plate 33. The spring 32 is adapted to be adjusted to apply an upward force on the movable unit comprising the diaphragm It, the rod 3i and the diaphragm 25 for overcoming the effect of the weight of these parts.

The casing l4 preferably has mounted'on the" upper wall l6 thereof, a straight bore tube 43 which is connected to a suitable source of pressure fluid at a regulated pressure, the pressure fluid preferably being compressed air. The lower end of the tube 40 is enlarged to provide an expanding area chamber 4 I. The lower end of the chamber 4| is provided with a closure 42 having a valve seating portion 43 formed therein. A valve seating member 44 is provided which is adapted to be spaced with respect to the port 43 for controlling the discharge of pilot fluid as hereinafter explained. The valve seating member 44 has a stem 45 bearing on an adjusting collar 45 having internal threads in engagement with threads 4! on the upper end of the rod 3!. A retainer spring 48 is interposed between the adjusting collar 46 and the diaphragm 25. A tube 50 is provided, suported and adjustably clamped by a fastener 49 at its outer end in a tube support block The interior'of the tube 50 is in communication with the tube 4!! and a tubular rod 52 extends within the tube 59.

The tubular rod 52 is provided with a streamlined tip 53 having a straight portion 53a of a length sufflcient to establish laminar flow. The tubular rod 52 has an interior bore 54. A piezometer gap or opening 55. of a size such as to avoid disturbance of the laminar flow is provided in communication with the bore 54 for transmitting the pressure at the gap 55. v The internal diameter of the tube 50 and the external diameter of the tubular rod 52 are preferably such as to provide an annular space therebetween which has a radial width such as to insure laminar flow of the pilot fluid passing therealong.

The bore 54 is connected, preferably by a flexible conduit 56, to a suitable pressure responsive device or instrument I. a pressure gauge for indicating being illustrated.

The tubular rod 52 preferably extends through a tube 6|, a gland 62 and packing 53 being provided for adjust/ably positioning the tubular rod 52 with respect to the tube 50. The tube 5! is supported and adjustably clamped by a fastener in a tube sup ort block 54 in axial alinement with the tube 50. The tube 6| functions as an vide a gap 6'! of the desired length. The end 56 of the tube 50 is preferably beveled to avoid any 4 obstruction of the flow of the fluid discharging from the tube 50.

The variation of the length of the gap 51 permits or regulated departure from the exact square root function. The discharge of pilot fluid from the laminar flow tube 50 against the impact end 65 of the tube 6| creates a static pressure in the space in the interior of the tube Bl outside the tubular rod 52. This static pressure is proportional to the square of the velocity of the fluid impinging upon the tube 6|. The interior space is in communication through a conduit 68 with the chamber 28 so that this static pressure is effective in'that chamber.

The exterior of the straight bore tube 40 and of the laminar flow tube 50 are preferably covered with heat insulating material 69 for purposes to be explained.

In laminar flow all fluid particles move in parallel lines without crosswise mixing, and the pressure loss or drop, resulting from laminar flow, is directly proportional to the average velocity in the cross section of the tube.

Fluid flowing through the primary metering device I 0 produces a higher static pressure which is effective through the pipe I2 in the chamber 2! and a lower static pressure which is effective through the pipe l3 in the chamber 22, the differential of these pressures acting on the diaphragm I8 and thereby exerting a control effect on the pilot valve 44 through the rod 3|.

.Pilot fluid is delivered at regulated pressure through the tube 40, and a portion thereof is discharged in accordancewith the positioning of the valve 44 with respect to the seat 43. The other portion of the pilot fluid passes into the tube 55 where it is guided by the straight portion 53 of the tubular rod 52 and laminar flow established. The fluid, with laminar flow, passes along the annular space between the tube 50 and the tubular rod 52 and produces a pressure drop in the portion of the tube 50 between the piezometer gap 55 and the terminal end 66 of the tube 50. This pressure drop, for a particular setting of the gap 61, is a first power function of the velocity of the pilot fluid in the laminar flow tube and this pressure at the gap 55 is effective through the bore 54 and the conduit 56 and may be read on the gauge I.

The fluid dischargin at the terminal end 65 of the laminar flow tube is effective in the impact tube 6! and sets up within the tube 6| 8. pressure which is a second power function of its velocity. The pressure effective within the tube BI is transmitted through the conduit 58 to the chamber 28 where it is applied against the diaphragm 2.5. The force applied in the chamber 28 against the diaphragm 25, which diaphragm 25 is connected to the rod 3|, is in opposition to the force applied against the diaphragm (8 from the primary metering device Ill. The difierential effective from the primary metering device It on the diaphragm I8 is proportional to the second power of the fluid flow to be measured.

For a particular flow a differential will be established effective against the diaphragm l8 and opposing this for balanced conditions and for equilibrium an equal force will be exerted in the chamber 28 against the diaphragm 25. The pilot valve 44 will be positioned to control the discharge through the port 43. The pressure of the pilot fluid available for laminar flow is thus determined and this pressure in turn determines the pressure applied in the chamber 28 to maintain equilibrium conditions. Upon a change in the rate of flow From this it will be seen that Ab'Ki; 11 6 Rr==Kzq The gauge reading at the gauge I, on a scale of uniform divisions; is acordi'ngly"ardirect 'measure of the flow to be measured. The length of'th'e laminar'passagemaybevaried as. desired by'loosening the gland!!! and moving, the tubular rod '52 to position the gap 55 the desired distance from. the terminal end 86' of the tube 50. This adjustment permits of'making the maximum reading of the. gage I agree with different maximum rates of flow in the primary metering device ID, or agree with the same maximum now in primary metering device fll" of difierent ratio.

The gap between the terminaf endGB- of the laminar flow tube 50 and the terminaf end 65 of the impact tube El mayal'so-be varied by loosening' the fastener H1 in the tube support 64 and sliding the impact tube 6| to'the position desired; This adjustment" permits of accommodation to primary metering devices HT which depart slightly from the exact second,power'relationbetween the differential produced and the rate of flow corresponding; thereto". The kinematic viscosity of the'pilot fluid increases with the temperature and'the curve of these quantities is flatter for lower temperatures. In order to take advantage of the reduced temperature attendant upon the expansionof the pilot fluid for delivery to the bore 40, the heat insulating material'fis covers-'the tube 4W. and=the tube 5!! to retain the lower temperature. This reduces the creep which mayfollow ambient temperature effects;

I claim:

1. In a mudmeter, a laminar flow tube connected to a source of pressure fluid means for varying the effective length of said; tube, anxexpansible chamber having amovable. wall portion, an impact tube positioned adjacent the discharge end of said laminar flow tube and incommunication with said chamber, means for applying a force to be measured against said movable: wall portion, valvemeans actuated'by the positioning of said movable wall portion for varyingv the rate offiow through said laminar fiow' tub'e and for maintaining the forces acting upon: saidv movable wall-portion: in balance, and-means responsive to the pressure offiuid in said laminar flow tube.

'2. In a fluid meter, alaminar flow tubeocom- 6 neoted to a, sourceo! pressurefluid; an blechamber having a. movable: walls: portion, at: impact tube positioned adjacent the dischargeend of said laminar flow tube andincommunication with said? chamber, meansior: applyingra forcetorbe measured against said movable-walk portion; means controlled" bysaid force forcom trolling-thepressure of the fluid from said'source supplied to said tube, means for permitting vary q ing the distancebetween said impact tube and the discharge end of theIam-inan flow tube',and means-responsive to the pressure ofifl uidin said laminar fiowtube;

3. In a'fiuidmeter; a ,tube connected toasourca of pressurefiuid', mounting means-for said tube; a rod positioned coaxiaily within said tube with the. adjacent'surfaces of the tubeand'ofthe rod closely'spa'ced to provid'e a passageway forl'aminar'fi'ow; mounting" means for said rod disposed beyond the discharge end of said tube, at least one or said'mounting means permittingrela-tive positioning; or said rodand-said tube longitudinally for determining the eii'ective length of" the laminar flow passageway, means actuated by the flow of said fl'uidjthroug'h saidtubefor producing a pressure proportional to the square of saidflow, and; means responsive to the pressure offiu-id in said laminar flow' passageway for" producing an effect proportional to. said flow:

4; In a fluid meter, a tube connected toa source of pressure fluid-,a rod positioned coaxi ally within, said-tube withthe adjacentsurfaces of the tube. and of the rod closely spaced to provide a passageway forlaminar flow, saidrodhaving a pressure take-oh opening therein, means for permitting adjustable. positioning of said rod and. said tube for determining, the. effective length of thelaminar flow passageway, means actuated by the flow oi said. fluid through said tubefor producing a pressure proportional; to the square of said fiow,. and. means. responsive to the pressure offluidinsaid laminar flow passageway in communication. with. said opening for producing an effect proportional to said how.

5. In a fluid meten. a tube connected to a source of. pressure fluid, arod positioned coax.- ialiy within. said .tube with the. adjacent surfaces ofthe tube. andv of. the rod closely spaced to. provide a passagewayior laminar flow, saidrod having apiezometer opening. therein. and .an internal passageway in communication with said opening. means responsive to the, flow of; said fluidthrough said tube for produci'nga pressure proportional to the square of said. flow, and means incommunication with said internal spassageway for producing an reflect-proportional to said-flow;

6.. Inaflui'd metena: tube connected to a source of pressure fluidarod positioned coaxiallywithin said tuberWi-th the internal surface 01 thetube and; theexternalsurface of the rod-closely spaced to provide: a passageway for laminar. flow, said rod having apiezometer; opening in. the external surface thereof, and an internal passageway therethrough; in communication with said open.- ing;,m.eans for permitting. adjusting saidrod ion.- gitudinally with. respect to'said tube for varying the. efiective length of? the laminar flow passageway; means responsive. tozthe' flow of saidiluid through vsaidtube for producing a pressure. proportional'td the square of said. flow, and pres.- sure responsive; means in communication with said. internal-1 passageway responsive to the pres:

sure ofifluid in: said laminar flow passageways source of pressure fluid, means for controlling the pressure of the fluid from said source supplied to said tube, a rod positioned coaxially within said tube with the adjacent surfaces of the tube and of the rod closely spaced to provide a passageway for laminar flow, an expansible chamber having a movable portion connected to said controlling means, an impact tube in communication with said chamber and having an open end in spaced relation to the discharge end of the first tube, adjustable means for permitting varying' the positioning of said open and said discharge ends of said tubes, and movable means responsive to the pressure of fluid in the laminar flow section of said first tube.

8. In a fluid meter, a tube connected to a source of pressure fluid, means for controlling the pressure of the fluid from said source supplied to said tube, a rod positioned coaxially within said tube with the internal surface of the tube and the external surface of the rod closely spaced to provide a passageway for laminar flow, an expansible chamber having a movable portion connected to said controlling means, an impact tube in communication with said chamber and having an open end in spaced relation to the discharge endof the first tube, said rod extending within said impact tube, means for permitting adjusting said rod longitudinally with respect to said first tube for determining the efiective length of the laminar flow passageway, adjustable means for varying the positioning of said open and said discharge ends of said tubes, and movable means responsive to the pressure of fluid in the laminar flow passageway.

9. In a fluid meter, a tube connected to a source of pressure fluid, means for controlling the pressure of the fluid from said source supplied to said tube, a rod positioned coaxially within said tube with the adjacent surfaces of the tube and of the rod closely spaced to provide a passageway for laminar flow, said rod having a. piezometer opening therein and an internal passageway in communication with said opening, an expansible chamber having a movable portion connected to said controlling means, an impact tube in communication with said chamber and having an open end in spaced relation to the discharge end of the first tube, said rod extending within said impact tube, means for permitting adjusting said rod longitudinally with respect to said first tube for determining the effectivelength of the laminar flow passageway, and means responsive to the pressure of fluid in the laminar flow passageway.

10. In a fluid meter, a laminar flow tube connected to a source of pressure fluid, means for controlling the pressure of the fluid supplied to said tube, means for varying the effective length of said laminar flow tube, an expansible chamber having a movable portion connected to said controlling means, an impact tube in communication with said chamber and having an open end in spaced relation to the discharge end of the laminar flow tube, means for permitting varying the" spacing of said open and said discharge ends of said tubes and means responsive to the pressure of fluidin the laminar flow tube for producing an effect proportional to a fractional power of the flow through said laminar flow tube.

11. In a fluid meter, a laminar flow tube connected to a source of pressure fluid, means for controlling the pressure of the fluid supplied to said laminar flow tube, an expansible chamber having a movable portion connected to said controlling means, a Pitot tube in communication with said chamber and having an open end in spaced relation to the discharge end of the laminar flow tube, means for permitting varying the spacing of said open and said discharge ends of said tubes, and means responsive to the pressure of fluid in the laminar flow tube for producing an efiect proportional to a fractional power of the pressure in said expansible chamber.

12. In a fluid meter, including a fluid supply tube connected to a source of pressure fluid, a laminar flow tube connected to said supply tube, means for controlling the pressure of the fluid supplied to said laminar flow tube, an expansible chamber having a movable wall portion connected to said controlling means, an impact tube in communication with said chamber and positioned adjacent thedischarge end of said laminar flow tube, and means on said supply tube and said laminar flow tube for preventing heat absorption by the pressure fluid.

13. In a fluid meter, a movable wall portion responsive to a force to be measured, an expansible chamber having a second movable wall portion in alinement with and connected to said first mentioned wall portion, a laminar flow tube connected to a source of pressure fluid, means for varying the rate of flow through said laminar flow tube including valve means for controlling the discharge of fluid supplied from said source, operating connections between said valve means and said movable wall portions, an impact tube positioned adjacent the discharge end of said laminar flow tube and in communication with said expansible chamber, and indicating means responsive to the pressure of fluid in said laminar flow tube.

14. In a fluid meter, a tube connected to a source of pressure fluid, a tubular member positioned coaxially within said tube with the adjacent suriaces of the tube and of the tubular member closely spaced to provide a passageway for laminar flow, means for positioning said tubular member longitudinally with respect to said tube for determining the eficctive length of the laminar flow passageway, means actuated by the flow of said fluid through said tube for producing a pressure proportional to the square of said flow, and means in communication with the interior of said tubular member responsive to the pressure drop through said laminar flow passageway for producing an effect proportional to said flow. 1

15. In a fluid meter, a tube connected to a source of pressure, a tubular member positioned coaxially within said tube with the adjacent surfaces of the tube and of the tubular member closed spaced to provide a passageway for laminar flow, means beyond the discharge end of said tube for supporting said tubular member at its outer end portion, said tubular member having an internal end portion for setting up laminar flow in said passageway, and means in communication with the interior of said tubular member responsive to the pressure of fluid in said laminar flow passageway.

16. In a fluid meter, a tube connected to a source of pressure fluid, a tubular member positioned coaxially within said tube with the internal surface of the tube and the external surface of the tubular member closely spaced to provide a passageway for laminar flow, the outer end portion of said tubular member extending beyond the discharge end of said tube, said tubular member having anninternal endportion for setting up REFERENCES CITED The following references are of record in the file of this patent:

Number 10 UNITED STATES PATENTS Name Date Spink June 13, 1933 Moller Aug. 28, 1934 Naiman June 23, 1936 Goetzl June 27, 1939 Ricardo et a1. Aug. 20, 1940 Hardebeck Sept. 29, 1942 Gooden Mar. 28, 1944 

